I don't think that would be possible, but must confess it's an unusual requirement.
Sessions should always run independently, so signing in with different browsers / at the same should be supported on usually any web application.
If you still need it, I would look into the following:
I don't know if the above is possible to achieve, that's just what I would look into, but again.. I would fight back on this requirement, doesn't seem like a web standard thing to be doing
Power Apps Portals Super User
@OliverRodrigues Thanks for your valuable response.
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